Intracorporeal Component for a Percutaneous Device

ABSTRACT

An intracorporeal portion of a percutaneous device for a joint disarticulation prosthesis or joint replacement prosthesis, the intracorporeal portion having an extracorporeal portion or having means for rigidly coupling directly to an extracorporeal portion, the extracorporeal portion being for location exterior to the skin, the intracorporeal portion having an articulating component for articulating with an articulating surface, wherein the articulating component is intracorporeal when installed in a human or animal subject.

FIELD OF THE INVENTION

The present invention relates to an intracorporeal portion orintracorporeal component for a percutaneous device for use in a jointdisarticulation prosthesis or a joint replacement prosthesis, includingshoulder or hip disarticulation prostheses.

BACKGROUND TO THE INVENTION

Disarticulation is the amputation of a limb through a joint. Often,disarticulation occurs without the cutting of bone. For example, hipdisarticulation is an amputation through the hip joint, removing theentire leg at the hip joint. Shoulder disarticulation is an amputationthrough the shoulder joint, removing the entire arm at the shoulderjoint. Disarticulation is also known as exarticulation.

Amputees who have undergone either disarticulation often wish to befitted with prosthetic equipment that will allow them to replicate atleast a portion of the function of the missing limb.

Unlike in a transhumeral amputation or transfemoral amputation, wherethe shoulder and hip are left intact and the patient has ahumeral/femoral stump to attach an external prosthesis to, in a shoulderor hip disarticulation the patient has no residual limb stump extendingfrom the scapula or pelvis to be received in the socket of an externalprosthesis (exoprosthesis) and to provide a stable anchoring point forthe prosthesis. In a shoulder or hip disarticulation the prosthesis mustsomehow be secured around the patient's pelvis/scapula. It is thereforedifficult and cumbersome to reliably secure shoulder/hip disarticulationprostheses to patients.

For a hip disarticulation prosthesis, an exoprothesis having a hipjoint, a knee joint, and an ankle joint should be provided. Typically aprosthetic device for hip disarticulation would have a large socket thatreceives and is affixed to the lower portion of the torso of theamputee, the socket being strapped around the patient's body. An exampleof a hip disarticulation prosthesis is described in U.S. Pat. No.7,153,329 (Wilson). For a shoulder disarticulation prosthesis, anexoprosthesis having a shoulder joint, elbow joint and wrist jointshould be provided. Typically a prosthetic device for a shoulderdisarticulation would have a large socket that receives and is affixedto the shoulder area and is secured by strapping the socket around thepatient's torso.

Such hip and shoulder disarticulation prostheses are uncomfortable towear and use and suffer from numerous problems at the skin-socketinterface. Focal points of increased stress caused by non-uniformpressure distribution can lead to skin-related complications, whilst theunnatural microbial environment generated in the socket is detrimentalto the maintenance of healthy tissues. Furthermore, disarticulationexoprostheses are difficult to secure to a patient and can be unstable.

Even in transhumeral or transfemoral amputation, where the patient has ahumeral or femoral stump to attach an external jointed limb prosthesisto, the patient will still have difficulty using the prosthesis as it isdifficult for the patient to control and move the joint(s) of theexternal prosthesis.

Most jointed exoprostheses fall into two categories, these beingbody-powered prostheses and motor-actuated/myoelectric prostheses. Abody-powered prosthesis is powered and controlled by gross bodymovements. For a prosthetic arm with an elbow joint and/or a grippingelement (often a hook), these movements, usually of the shoulder, upperarm, or chest are captured by a harness system, which is attached to acable that is connected to the exprosthesis, to control the prosthesisjoint(s). However, such body-powered prostheses are not cosmeticallypleasing and are difficult to control.

The myoelectric prosthesis is an external prosthesis that is linked tothe residual musculature through an external electrode placed on theskin. These electrodes pick up the faint electrical signal produced byvoluntary contractions of the residual muscles. This activates anelectrically powered external prosthesis. However, the link is crude andthe movements which can be produced are therefore relatively crude. Suchprostheses are also heavy and difficult to use.

SUMMARY OF INVENTION

According to a first aspect of the invention, there is provided anintracorporeal portion of a percutaneous device for a jointdisarticulation prosthesis or joint replacement prosthesis, theintracorporeal portion having an extracorporeal portion or having meansfor rigidly coupling directly to an extracorporeal portion, theextracorporeal portion being for location exterior to the skin, theintracorporeal portion having an articulating component for articulatingwith an articulating surface, wherein the articulating component isintracorporeal when installed in a human or animal subject.

The intracorporeal portion of the present invention can be used as partof a joint disarticulation prosthesis, for a subject that has had ajoint disarticulation. A device incorporating the intracorporeal portionprovides a prosthesis that does not have the problems associated withthe skin-socket interfaces of prior art disarticulation prostheses. Byproviding the intracorporeal portion with an articulating component, theintracorporeal portion can articulate with a corresponding articulatingsurface, and the intracorporeal portion therefore replaces part of thesubject's joint. The articulating component of the device effectivelyforms one component of a joint, the articulating surface forming theother component of the joint. Suitably, at least a portion of theextracorporeal component is located exterior to the skin when installedin a subject. Suitably, at least a portion of the extracorporealcomponent passes through the skin when installed in a subject.

The intracorporeal portion of the present invention can also be used aspart of a joint replacement prosthesis, for a subject that has had apartial limb amputation and requires a joint replacement prosthesis. Theterm joint replacement prosthesis refers to a prosthesis for replacing asubject's joint. Joint replacement prostheses can be partial (replacingpart of a subject's joint) or total (replacing the whole a subject'sjoint). Joint replacement prostheses may be inside the body(endoprostheses) or external (exoprostheses). By providing theintracorporeal portion with an articulating component, theintracorporeal portion can articulate with a corresponding articulatingsurface, and the intracorporeal portion therefore replaces part of thesubject's joint. Muscle from the subject's residual limb can be attachedto the intracorporeal portion of the percutaneous device when it isinstalled in the subject. This provides a direct link between thesubject's musculature and the percutaneous device, and allows thesubject to move the percutaneous device using their own residualmuscles. The extracorporeal portion of the percutaneous device can havemeans for attaching an exoprosthesis, therefore the patient can move theexoprosthesis by using their muscles, attached to the intracorporealportion of the percutaneous device, to move the the percutaneous device.This device provides a means for replacing a joint in a subject that hashad a limb amputation wherein the device does not suffer from theproblems of prior art body-powered or myoelectric jointed exoprostheses,such as difficulty in control of movement at the joint.

The term subject or patient as used herein refers to a human or animalsubject.

The articulating component can articulate with the articulating surfacedirectly, or via a prosthetic bearing surface.

Percutaneous devices are devices that penetrate the skin of a human oranimal body. Osseointegrated percutaneous devices are known in the priorart, for example for providing secure means of attaching an externalprosthesis to the bone within a limb stump without the use of bulky andinconvenient braces, straps or sockets. WO 01/97718 (University CollegeLondon) discloses an osseointegrated percutaneous prosthesis comprisinga first component shaped for implantation into bone of a limb stump, asecond component for location between the bone and the skin and a thirdcomponent for location exterior to the skin. None of the osseointegrateddevices of the prior art provide means for securing a prosthetic limb toa subject which has undergone a joint disarticulation or wherein thesubject does not have a residual limb stump (i.e. a residual femoral orhumeral stump) to which an osseointegration device can be implanted (forexample, by implantation into the intramedullary cavity of bone in thestump).

According to a second aspect of the invention there is provided apercutaneous device of or for a shoulder or hip joint disarticulationprosthesis, the percutaneous device comprising an intracorporeal portionand an extracorporeal portion for location exterior to the skin, thepercutaneous device further comprising an articulating component, thearticulating component comprising a ball or socket component. Preferablythe articulating component is intracorporeal when installed in a humanor animal subject. In other words, the articulating surface is locatedinside the body in use.

The natural shoulder and hip joint are ball and socket joints, wherein aball of one bone is received in a cavity or socket of another, allowingsome degree of rotary motion in every direction. Suitably thepercutaneous device is used as a shoulder or hip disarticulationprosthesis, or as part of a shoulder or hip disarticulation prosthesis,and provides a prosthesis that does not have the problems associatedwith the skin-socket interfaces of prior art disarticulation prostheses.By providing the percutaneous device with an articulating componentwhich is either a ball or socket component, the percutaneous device canarticulate with a corresponding socket or ball in use, as appropriate,and the percutaneous device thereby replaces part of a subject'sshoulder or hip joint.

Preferred features of the first and second aspects of the invention aredescribed below.

Preferably the articulating component is intracorporeal when installedin a human or animal subject. Preferably the articulating surface isintracorporeal in use.

Preferably the articulating component is integral with or rigidlycoupled to the intracorporeal portion or the extracorporeal portion ofthe percutaneous device in use. The articulating component is thereforenon-movable relative to the intracorporeal portion or extracoroporealportion of the device. Preferably the intracorporeal portion has a bodycomponent, the articulating component being integral with or coupled tothe body component in use.

Preferably the articulating component comprises a ball component or asocket component and the device articulates with an articulating surfaceof a ball and socket joint, when implanted. Suitably the device may befor use as part of a shoulder or hip disarticulation prosthesis.

Preferably the device is adapted for use in an anatomical shoulderprosthesis or anatomical hip prosthesis. In an anatomical shoulder orhip prosthesis, the component that replaces the proximal end of thehumerus or femur has a ball component, which articulates with a socketin the scapula or pelvis (which may be a natural socket or a replacementsocket shell). Preferably the articulating component is a ballcomponent, the ball component being intracorporeal when installed in ahuman or animal subject. Preferably the ball component is comprised aspart of the intracorporeal portion of a percutaneous device, such thatthe ball component is within the body of a subject when installed.

Preferably the articulating component articulates with an articulatingsurface of a hinge joint when implanted in a subject. Hinge joints inthe human body can be found, inter alia, at the knee, elbow and ankle.The articulating component could of course articulate with anarticulating surface of joints, other than ball-and-socket or hinge typejoints.

Preferably the articulating component articulates with a naturalarticulating surface of a subject's joint in use. Suitably, in use, thearticulating component can articulate with the articulating surfacedirectly or via a prosthetic bearing surface. For example, thearticulating component may be adapted (i.e. sized and shaped) toarticulate with an articulating surface of a patient's hip joint.

Preferably the intracorporeal portion comprises a proximal end and adistal end, the articulating component being located at the proximal endof the intracorporeal portion when installed in a subject. In thiscontext the term proximal means located near or towards the centre ofthe subject's body or limb when the device is installed and distal meanslocated away from the centre of the body or limb when the device isinstalled.

Preferably the articulating surface is a hip socket or a shoulder socketof a subject, or is a prosthetic bearing surface installed in a hipsocket or shoulder socket of a subject in use. For example, for a hipdisarticulation, the articulating component may be a ball component thatmay articulate with a prosthetic socket liner such as a prostheticacetabular shell or cup. The percutaneous device is able to pivotrelative to the subject's pelvis/scapula, and provides a stable meansfor coupling an external limb prosthesis to the subject and fortransmitting the load from the external limb prosthesis through thesubject's bone, rather than through the subject's soft tissues. Unlikein prior art percutaneous devices for attachment of external limbprostheses, the intracorporeal portion of this aspect of the inventionis not osseointegrated, and hence the percutaneous device can be pivotedrelative the subject's bone, allowing replication of the action of thepatient's joint. The present invention therefore provides a means forcoupling an external limb prosthesis to a subject's skeleton, via anarticulating joint, without rigidly fixing the percutaneous prosthesisto the subject's bone.

Preferably the articulating surface is a condylar surface of a subject'sknee joint and the articulating component is a corresponding tibialhinge component for articulating with the condylar surface. Suitably thetibial component of the percutaneous device is adapted to articulatewith the condylar surface of a subject's knee joint, for use in a kneejoint disarticulation prosthesis.

Preferably the articulating component articulates with a prostheticarticulating surface in use. Suitably, the articulating surface isprosthetic, having been implanted in the subject's body. Preferably, thearticulating surface is a prosthetic articulating surface of anendoprosthesis.

Preferably the articulating component comprises a socket component, thesocket component articulating with a ball component of a bone anchoredendoprosthesis in use. In this context, the term endoprosthesis is usedto refer to a prosthesis that is installed in a subject's bodyinternally and the term exoprosthesis is used to refer to a prosthesisthat is applied externally to a subject's body. The socket component ofthe percutaneous device can, for example, articulate with a ballcomponent of a bone anchored glenoid prosthesis when used for a shoulderdisarticulation prosthesis. The percutaneous device is therefore able topivot relative to the subject's pelvis/scapula as appropriate, andprovides a stable means for coupling an external limb prosthesis to thesubject and transmitting the load from the external limb prosthesisthrough the subject's bone, rather than through the subject's softtissues. Unlike in prior art percutaneous devices for attachment ofexternal limb prostheses, the precutaneous device of this preferredaspect of the invention is not osseointegrated, and hence thepercutaneous device can pivot relative the subject's bone, allowingreplication of the action of the patient's hip or shoulder joint. Thepresent preferred aspect of the invention therefore provides a means forcoupling an external limb prosthesis to a subject's skeleton, via anarticulating joint, without rigidly fixing the percutaneous prosthesisto the subject's bone. The percutaneous device couples to a boneanchored device having a ball component for articulating with the socketcomponent of the percutaneous device, providing a reverse anatomicaljoint configuration.

Preferably the articulating component comprises a tibial component forarticulating with a femoral hinge component of a knee endoprosthesis.Suitably, the tibial component can articulate with a condylar surface ofa femoral hinge component of an implanted endoprosthesis, theintracoporeal component forming part of a joint replacement prosthesisfor implantation in a subject that has undergone a transfemoralamputation. The intracoporeal component is therefore able to pivotrelative to the subject's femur, to provide a knee joint within thesubject's femoral stump. Similarly the articulating component could beadapted (i.e. sized and shaped) to articulate with a corresponding jointcomponent of an elbow joint of an implanted endoprosthesis, thepercutaneous device forming part of a joint replacement prosthesis forimplantation in a subject that has undergone a transhemoral amputation.The percutaneous device is therefore able to pivot relative to thesubject's elbow, to provide an elbow joint within the subject's humoralstump. Suitably, residual muscles at the site of the limb amputation canbe secured to the intracoporeal component when it is installed,anchoring muscle to the intracoporeal component and therefore allowingthe subject to control movement of the intracoporealcomponent/percutaneous device using their residual muscle at the limbstump.

According to a third aspect of the invention there is provided a kit fora joint disarticulation prosthesis or joint replacement prosthesis, thekit comprising an intracorporeal portion or percutaneous deviceaccording to the first or second aspect of the invention and anendoprosthesis having an articulating surface for articulating with thearticulating component. Suitably the endoprosthesis has a proximal endand a distal end, the articulating surface being at the distal end ofthe endoprosthesis when implanted. Suitably the endoprosthesis has boneanchoring means for rigidly attaching the endoprosthesis to a subject'sbone in use. The bone anchoring means may be a stem for engagement in aresected long bone. Preferably the endoprosthesis has a ball componentand bone anchoring means for rigidly attaching the endoprosthesis tobone in use. Preferably the endoprosthesis has a body portion formounting into bone, the body portion having a substantiallyfrustoconical taper with an integral screw formation extendingterminally therefrom whereby when the endoprosthesis is fixed in placeto bone by the screw formation, the taper of the body assists instabilising the endoprosthesis.

Suitably the device may be adapted for use in a reverse anatomicalshoulder prosthesis or a reverse anatomical hip prosthesis. In certaincircumstances it is desirable to reverse the natural anatomicalconfiguration of the joint, whereby in a reverse anatomical joint thesocket component of the joint is present on the proximal humeral/femoralcomponent and articulates with a ball component secured to thescapula/pelvis. Reverse anatomical configuration would be useful inparticular for use in shoulder joint disarticulations where thesubject's shoulder socket requires replacement, and wherein it may bedifficult to implant an anatomical glenoid shell that is large enough tostabilize the humeral prosthesis and prevent proximal migration.

Preferably the percutaneous device has bone anchoring means for rigidlyanchoring the device or at least part of the device to bone in use.Preferably the articulating component is extracorporeal when installedin a subject. Preferably the articulating component is located at adistal end of the extracorporeal portion when installed. Preferably thebone anchoring means comprises a screw formation extending from theproximal end of the percutaneous device when installed. Preferably thebone anchoring means further comprises a substantially frustoconicaltaper, the screw formation extending terminally from the frustroconicaltaper, whereby when the prosthesis is bone anchored by the screwformation, the taper assists in stabilising the percutaneous device.Preferably the articulating component is a ball component. Preferablythe ball component is comprised as part of the extracorporeal portion ofthe percutaneous device, such that the ball component is outside thebody of a subject when installed. Preferably the ball component islocated at the distal end of the extracorporeal portion when installed.Preferably the ball component articulates with a socket of anexoprosthetic device in use. The ball component of the percutaneousdevice therefore provides a stable, bone anchored support for couplingan external limb prosthesis to a subject's skeleton, via an articulatingball and socket joint.

With regard to the first, second and third aspects of the invention,when the articulating component is a ball component, the ball componentis preferably substantially spherical. The ball component is preferablya rounded, convex articulating surface.

Preferably the intracorporeal portion or percutaneous device furthercomprises a flange extending outwardly from the intracorporeal portionin use. The flange provides a large surface area for integration withskin and fibrous tissue. Preferably the flange is non-circular in shapein the plane transverse to the longitudinal axis of the intracorporealportion. The non-circular flange or enlarged distal portion providesrotational stability to a socket of an exoprosthesis installed on thestump and prevents spinning of the socket on the stump (when theintracorporeal portion is not coupled to the extracorporeal portion, theintracorporeal portion being implanted fully under a patient's skin).For example, the non-circular flange or enlarged distal portion may beoval shaped.

Preferably at least a portion of the intracorporeal portion is porous.Advantageously, high porosity zones enhance tissue ingrowth (skin and/ormuscle tissue), whilst the less porous zone maintains strengthcharacteristics of the intracorporeal portion.

Preferably the intracorporeal portion has a plurality of apertures forattaching a subject's soft tissue to the intracorporeal portion.Preferably the apertures comprise through-holes. Preferably the diameterof each aperture is around 1 to 2 mm. These macro-sized apertures aresuitably large enough to allow a needle and polymer suture material(such as Fiberwire®) to pass through, such that muscle can be secured tothe flange using sutures. The sutures may be permanent or temporary.After implantation, over time, muscle tissue can ingrow through themacro-sized apertures, further securing the device to the nearby tissue.

Preferably the intracorporeal portion and extracorporeal portion areseparate pieces, and are rigidly coupled together in use. Suitably,where the intracorporeal portion and extracorporeal portion are separatepieces, at least a portion of the extracorporeal portion is locatedexterior to the skin when installed in a subject. Preferably theextracorporeal portion has a male pin and the intracorporeal portion hasa corresponding female socket for receiving the male pin of theextracorporeal portion. This allows the intracorporeal andextracorporeal portions to be coupled together. Preferably the devicehas means for securably coupling the intracorporeal and extracorporealportions together, releasably or non-releasably. Alternatively, theintracorporeal portion and extracorporeal portion are integral, forminga single piece percutaneous device.

Preferably at least a portion of the intracorporeal portion is treatedto promote cutaneous and/or muscle integration. Preferably at least aportion of the intracorporeal portion has a surface coating to promotecutaneous integration.

According to a fourth aspect of the invention there is provided apercutaneous device comprising an intracorporeal portion according tothe first or third aspect of the invention, the percutaneous devicefurther comprising an extracorporeal component for location exterior tothe skin, the extracorporeal component being integral with or coupled tothe intracorporeal component in use. The extracorporeal component mayhave any of the preferred features explained above.

According to a fifth aspect of the invention there is provided a jointdisarticulation prosthesis or joint replacement prosthesis including anintracorporeal portion or percutaneous device according to thepreviously described aspects of the invention. Preferably there isprovided a shoulder or hip disarticulation prosthesis including apercutaneous device according to the previous described aspects of theinvention.

According to a sixth aspect of the invention there is provided anintracorporeal component for a percutaneous device, the intracorporealcomponent having means for attachment to a bone, the intracorporealcomponent being adapted for being implanted fully subcutaneously suchthat no portion of the intracorporeal component extends through the skinwhen implanted in a subject, the intracorporeal component having afemale socket for receiving a corresponding male pin of anextracorporeal component, the extracorporeal component being forlocation exterior to the skin. The female socket and male pin providedallow for coupling of the extracorporeal component to the intracorporealcomponent if desired. Suitably, a portion of the extracorporealcomponent is located exterior to the skin when installed. Theintracorporeal component will be fully under the skin when implanted. Ifthe extracorporeal component is not installed in the intracorporealcomponent, the female component of the intracorporeal component will befully covered by skin.

This differs from prior art systems, such as that disclosed in US4158895 (Reswick), wherein the distal end of the intracorporeal supportextends through the skin when implanted, such that the female socket forattachment of the extracorporeal component is exposed and the pin of theextracorporeal component can be coupled to the intracorporeal supportwithout further medical intervention to expose the female socket. Byimplanting the intracorporeal component such that it is fully under theskin, with no part of it extending through the skin, the intracorporealcomponent can be left in the patient indefinitely as a stump extender.The intracorporeal component can have a distal flange or enlarged distalportion that extends outwardly from the intracorporeal component in use,the flange or enlarged distal portion being non-circular in shape in theplane transverse to the longitudinal axis of the intracorporealcomponent. The non-circular flange or enlarged distal portion is alsoadapted for being implanted fully subcutaneously, such that no portionof the intracorporeal component extends through the skin when implanted.The non-circular flange or enlarged distal portion provides rotationalstability to a socket of an exoprosthesis installed on the stump andprevents spinning of the socket on the stump. For example, thenon-circular flange or enlarged distal portion may be oval shaped. Themeans for attachment to a bone can be any suitable means for rigidlyattaching the device to a bone; for example, it may be a stem forinsertion into an intramedullary cavity of a bone stump, or may be acollar that can rigidly receive a bone stump therewithin.

According to a further aspect of the invention there is provided a kitfor a percutaneous device, the kit comprising an intracorporealcomponent according to the sixth aspect of the invention, the kitfurther comprising an intracorporeal plug receivable in the femalesocket of the intracorporeal component, the plug being fullyintracorporeal when installed. Suitably, the plug is adapted to be fullysubcutaneously installed, such that no portion of the plug extendsthrough the skin when implanted.

According to a further aspect of the invention there is provided apercutaneous device, the device comprising an intracorporeal componentaccording to the sixth aspect of the invention and an extracorporealcomponent for location exterior to the skin, the extracorporealcomponent having a male pin receivable in the female socket of theintracorporeal component for rigidly coupling the extracorporealcomponent to the intracorporeal component.

According to a further aspect of the invention there is provided anintracorporeal component for a percutaneous device, the intracorporealcomponent having means for attachment to a bone, the device furthercomprising a flange extending outwardly from the intracorporealcomponent in use, the flange being non-circular in shape in the planetransverse to the longitudinal axis of the intracorporeal component. Thenon-circular flange or enlarged distal portion provides rotationalstability to a socket of an exoprosthesis installed on the stump andprevents spinning of the socket on the stump. The flange may be anenlarged distal portion that extends outwardly from the intracorporealcomponent. The longitudinal axis of the intracorporeal component is theaxis parallel with the axis of implantation of the component in asubject. The flange may be oval in cross-sectional shape for example.

According to a further aspect of the invention there is provided amethod of installing in a subject an intracorporeal portion orpercutaneous device for a joint disarticulation prosthesis or jointreplacement prosthesis as described in the first or second aspects ofthe invention, the method comprising the steps of

-   -   (i) implanting the intracorporeal portion under the skin;    -   (ii) coupling the articulating component with the articulating        surface such that the articulating component can articulate with        the articulating surface in use.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be moreparticularly described by way of example only with reference to theaccompanying drawings, wherein:

FIG. 1 shows a diagrammatic part cross-section through an embodiment ofa percutaneous device for use in an anatomical hip disarticulationprosthesis, the device shown installed in a subject, the device having aball component received in a subject's hip socket;

FIG. 2 shows a diagrammatic part cross-section through an embodiment ofa percutaneous device for use in an anatomical shoulder disarticulationprosthesis, the device shown installed in a subject, the device having aball component received in a subject's shoulder socket;

FIG. 3 shows a diagrammatic part cross-section through an embodiment ofa percutaneous device for use in a reverse anatomical shoulderdisarticulation prosthesis, the device shown installed in a subject, thedevice having a ball component that articulates with an exoprosthesis;

FIG. 4 shows a diagrammatic part cross-section through an embodiment ofa percutaneous device for use in a reverse anatomical shoulderdisarticulation prosthesis, the device shown installed in a subject, thedevice having a socket component that articulates with a bone-anchoredendoprosthesis.

FIG. 5 shows a diagrammatic cross-section through an embodiment of abody component of the intracorporeal portion of a percutaneous device,similar to the FIG. 1 embodiment, for use in an anatomical hipdisarticulation prosthesis; the device has a removable portion includingthe extracorporeal portion of the device, the removable portion notbeing present in the diagram;

FIG. 6A shows an exploded diagrammatic cross-section through anembodiment of a body component of a percutaneous device, similar to theFIG. 5 embodiment, for use in an anatomical hip disarticulationprosthesis; the device has a removable portion including theextracorporeal portion of the device, the removable portion shownseparate from the body component in the diagram;

FIG. 6B shows a diagrammatic cross-section through the embodiment ofFIG. 6A, but with the removable portion installed in the body component;

FIG. 7 shows a constrained femoral head inserted in prosthetic cup, thefemoral head for attachment to the body component of FIG. 5 or 6A, andthe prosthetic cup for installation in the subject's acetabulum;

FIG. 8 shows an alternative femoral head and prosthetic cup system tothat of FIG. 7, the femoral head being held captive in the prostheticcup by a ring attached to the prosthetic cup;

FIG. 9 shows a diagrammatic part cross-section through an embodiment ofa percutaneous device for use in a joint replacement prosthesis for apatient having undergone a transfemoral amputation, the device showninstalled in a subject, the device having a tibial component thatarticulates with an endoprosthesis.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present embodiments represent currently the best ways known to theapplicant of putting the invention into practice. But they are not theonly ways in which this can be achieved. They are illustrated, and theywill now be described, by way of example only.

Referring to FIG. 1, this shows a percutaneous device 10 installed in asubject 11. The percutaneous device 10 has an intracorporeal orsubcutaneous portion 12 which resides under the skin 14 when the deviceis installed and an extracorporeal or external portion 16 which extendsfrom the skin when the device is installed. The device may be made upfrom separate components connected together, or the components may beformed integrally.

In FIG. 1, the percutaneous device 10 is shown installed at thesubject's hip. The device 10 has a ball component 20 at its proximal endwhen installed which is received in and articulates with the subject'snatural hip socket (the acetabulum) 22 in the subject's pelvis 24.Alternatively the ball component 20 may be received in and articulatewith an artificial liner in the subject's hip socket, such as aprosthetic acetabular shell (not shown in the figures). The ballcomponent is a substantially spherical, convex, articulating surfacethat is able to articulate with a subject's natural or prosthetic hipsocket.

Percutaneous devices with ball components of a range of different sizescan be provided to allow for differences between patients.Alternatively, the ball component may be provided as a separatecomponent from the body of the intracorporeal portion 12 of the device,for assembly together before installation in a subject. In this way, theball component may be provided as a modular component for use with asingle percutaneous device body, and the desired ball size can beselected and assembled to the percutaneous device body.

The percutaneous device 10 has a flange or flange assembly 18, extendingoutwardly from the longitudinal axis of the intracorporeal portion 12.The flange 18 may be integral with the body of the intracorporealportion 12, or may be a separate piece which is attached to theintracorporeal portion 12. The flange assembly provides a large surfacearea for integration with skin and fibrous tissue. The percutaneousdevice may be installed in a one-stage procedure or in a two-stageprocedure wherein the intracorporeal portion 12 of the device 10 isinstalled first and allowed to integrate before the flange 18 andextracorporeal portion 16 are attached. Alternatively, theintracorporeal portion 12 and flange 18 can be is installed first andallowed to integrate before the extracorporeal portion is attached. Theflange is curved in shape, the surface of the distal portion beingconvexly curved and the surface of the proximal portion being concavelycurved. This helps to prevent stresses being applied to the soft tissuesthat lie over the peripheral edge of the flange assembly.

The percutaneous device may have means at the distal end of theextracorporeal portion 16 for attachment to an artificial leg (notshown).

Referring to FIG. 2, this shows a percutaneous device 110, similar tothe device 10 of FIG. 1, except that the device 110 of FIG. 2 isinstalled at the subject's 111 shoulder. Similar to the device of FIG.1, the device of FIG. 2 has an intracorporeal or subcutaneous portion112 which resides under the skin 114 when the device is installed, anextracorporeal portion 116 which extends from the skin when the deviceis installed, and a flange assembly 118 extending outwardly from thelongitudinal axis of the intracorporeal portion 112. The device 110 hasa ball component 120 at its proximal end when installed which isreceived in and articulates with the subject's natural shoulder socket(the glenoid fossa) 122 in the subject's scapula 124. Alternatively theball component 120 may be received in and articulate with an artificialliner in the subject's glenoid socket, such as a prosthetic glenoidshell (not shown in the figures). The ball component is a substantiallyspherical, convex, articulating surface that is able to articulate witha subject's natural or prosthetic shoulder socket. The percutaneousdevice may have means at the distal end of the extracorporeal portion116 for attachment to an artificial arm (not shown). All of thepreferred features described in relation to the device of FIG. 1 may beapplied in the device of FIG. 2 also.

Referring to FIG. 3, this shows a percutaneous device 210 installed in asubject 211 at the shoulder. The percutaneous device 210 has anintracorporeal or subcutaneous portion 212 which resides under the skin214 when the device is installed and an extracorporeal portion 216 whichextends from the skin when the device is installed, and a flangeassembly 218 extending outwardly from the longitudinal axis of theintracorporeal portion 212. Unlike the embodiment of FIG. 2, thepercutaneous device 210 is used to provide a reverse anatomical shoulderprosthesis. In a reverse anatomical shoulder prosthesis the ball of theball-and-socket shoulder joint is provided on a glenoid prosthesiscomponent rather than on a humeral prosthesis component. In theembodiment of FIG. 3, the percutaneous device 210 comprises the glenoidprosthesis component of a prosthetic shoulder joint.

The extracorporeal portion 216 of the percutaneous device has a ballcomponent 220 at its proximal end when installed, which is received inand articulates with a socket component 242 on the end of anexoprosthesis 240. The intracorporeal portion 212 of the percutaneousdevice has a threaded screw shank 230 at its proximal end, to engageinto the bone of the glenoid cavity of the scapula 224. Between thescrew threaded shank 230 and the extracorporeal portion 216 is aplate/shoulder 234 that is circular in plan centred on the axis of thescrew thread shank 230 and with a transition from the plate portion 234to the shank 230 that is a substantially frusto-conical form 232tapering toward the shank 230. The plate/shoulder 234 may alternativelybe ovoid in plan. The frustoconical transition 232 enables the device tobe screw mounted to the glenoid surface to a substantial depth with areduction in fragmentation of the exposed glenoid face by the screwthreaded shank 230 and where the frustoconical surface 232 has astabilising effect so that when forces are applied to the joint, thedamage on the remaining glenoid bone is reduced. The frustoconicaltransition 232 is suitably coated with hydroxyapatite to encourageosseous integration and/or is micro-pitted.

In use, the ball component 220 of the percutaneous device is push-fittedor snap-fitted to the correspondingly shaped socket component 242 of theexoprosthesis 240. The exoprosthesis 240 may comprise an artificial armor may comprise an extension component for attachment to an artificialarm.

Referring to FIG. 4, this shows a percutaneous device 310 installed in asubject 311 at the shoulder. The percutaneous device 310 has anintracorporeal or subcutaneous portion 312 which resides under the skin314 when the device is installed and an extracorporeal portion 316 whichextends from the skin when the device is installed. The percutaneousdevice 310 of FIG. 4 is used to provide a reverse anatomical shoulderprosthesis. Unlike the embodiment of FIG. 3, the percutaneous device ofFIG. 4 does not comprise a glenoid prosthesis component of a prostheticshoulder joint. The percutaneous device of FIG. 4 has a socket component320 at the proximal end of the intracorporeal portion in use, whichcouples to a separate glenoid prosthesis component 350. Extendingoutwardly from the intracorporeal portion 312 is a flange assembly 318,which provides a large surface area which advantageously facilitates theintegration with fibrous tissue growth.

The glenoid prosthesis component 350 may be a Bayley-Walker® glenoidscrew prosthesis or similar, as known and described in the prior art,for example in GB 2 405 346 (Stanmore Implants Worldwide Ltd). Theglenoid prosthesis component 350 is anchored to the scapula 324 in use,the glenoid prosthesis component 350 having a threaded screw shank 351to engage into the bone of the glenoid cavity and where the head part ofthe screw is formed as a ball 352 to co-operatively engage with thebearing surface of the socket component 320 of the percutaneous device.

Between the screw threaded shank 351 and the ball 352 of the glenoidprosthesis component 350 is an intermediate portion comprising aplate/shoulder 353 that is circular in plan centred on the axis of thescrew thread shank 351 and with a transition from the plate portion 353to the shank 351 that is a substantially frusto-conical form 354tapering toward the shank 351. The plate/shoulder 234 may alternativelybe ovoid in plan. This frustoconical transition 354 enables the glenoidprosthesis component 350 to be screw mounted to the glenoid surface to asubstantial depth with a reduction in fragmentation of the exposedglenoid face by the screw threaded shank 351 and where the frustoconicalsurface 354 has a stabilising effect so that when forces are applied tothe joint, the damage on the remaining glenoid bone is reduced. Thefrustoconical transition 354 is suitably coated with hydroxyapatite toencourage osseous integration and/or is micro-pitted.

In use, the ball 352 of the glenoid prosthesis component 350 may bepush-fitted or snap-fitted to the correspondingly shaped socketcomponent 320 of the percutaneous device 310.

In use, the percutaneous device 310 of FIG. 4 can pivot relative to thebone anchored glenoid prosthesis component, thereby providing means forcoupling an external prosthesis to the subject.

It will be understood that the embodiment shown in FIGS. 3 and 4 couldbe used for a hip disarticulation.

Referring to FIG. 5, this shows a body component 412 of a percutaneousdevice 411 for use in an anatomical hip disarticulation prosthesis. TheFIG. 5 embodiment is similar to the FIG. 1 embodiment, however in theFIG. 5 embodiment the extracorporeal portion is a separate piece fromthe main body of the intracorporeal portion. The body component 412 isan intracorporeal or subcutaneous portion of the device when installed.The body component has a bore or hole 460, for receiving a removableportion of the percutaneous device (not shown in FIG. 5). The bore 460has a distal portion 460 a when implanted, that is hexagonal incross-section. The bore has a proximal portion 460 b, adjoining thedistal portion, the proximal portion being internally threaded (theinternal threading not being visible in FIG. 5).

Referring to FIGS. 6A and 6B, the body component 412 is similar to thebody component of FIG. 5, and common reference numerals are used in FIG.5, 6A and 6B for common features. Referring to FIGS. 6A and 6B, theremovable portion 461 of the percutaneous device is shown. The removableportion 461 has an intracorporeal portion 462 which resides under theskin in use, which together with the body component 412, forms theintracorporeal portion of the percutaneous device when assembled andinstalled. The removable portion 461 also has an extracorporeal portion463 which extends from the skin when the device is installed. Theremovable portion 461 comprises a hexagonal male component 464 thatcorresponds in shape to the hexagonal cross-section of the distalportion 460 a of the bore 460 of the body component, such that thehexagonal male component 464 can be tightly received in the distalportion 460 a of the bore. The hexagonal male component 464 has acentral bore 465 along its longitudinal axis, in which a bolt 466 can bereceived. The bolt has a threaded shank 466 a, which is threadedlyreceivable in the corresponding internally threaded proximal portion 460b of the bore 460 of the body component. The bolt has a head 466 b whichabuts an internal shoulder (not visible in the figures) of the hexagonalmale component 464, such that the threaded shank 466 a extends throughthe hole at the proximal end of the central bore 465 hexagonal malecomponent 464. In use, to attach the removable portion 461 to the bodycomponent 412, the hexagonal male component 464 is inserted in thedistal portion 460 a of the bore of the body component, and the bolt 466is inserted in the central bore 465 of the hexagonal male component 464;the bolt is threadedly engaged to the proximal portion 460 b of thebore, to secure the removable portion 461 with the body component 412.

Other means for securably attaching the separate extracorporeal portionto the body component 412 of the device can be used. For example, theextracorporeal portion may have a male portion receivable in a femaleportion (e.g. a bore) in the body component 412, the bore having across-hole for access transversely to the region of the end of the maleportion by a disassembly tool, similar to the cross-hole provided in themodular prosthesis disclosed in WO 02/47585 (Stanmore Implants WorldwideLimited).

An external spigot 467 may be attachable to the extracorporeal portion463 of the hexagonal male component 464, the external spigot 467 beingexternally splined for use in attachment of an external prosthetheticdevice to the percutaneous device.

The removable portion 461 may be fitted to the body component 412 duringinitial surgery to install the body component in a subject.Alternatively the body component may be installed without the removableportion 461 inserted, the body component being fully covered over by thesubject's skin and left for up to several months to allow tissue tointegrate with it. During the integration period, when the bodycomponent is entirely residing within the subject's body, the bore 460is filled with a plastic or metal fitting to prevent tissue ingrowth inthe bore. Further surgery can then be performed to install the removableportion 461 in the body component 412, the plastic or metal filling inthe bore 460 being removed during surgery prior to installation of theremovable portion 461 in the bore 460. Once installed, the removableportion 461 extends through the patient's skin.

The intracorporeal body component 412 can be left in a patientindefinitely, without installation of the removable portion 461. In thisway, the body component 412 can be used as a stump extender. Theextended stump can be received in the socket of an exoprosthesis.

When installed, the hexagonal male component 464 cannot rotate relativeto the body component 412, and the components are rigidly coupled to oneanother (i.e. non-movably coupled). Of course the distal portion 460 aof the bore and the hexagonal male component 464 could havecross-sectional shapes other than hexagonal. If the male component 464has a circular cross-section, it may include a lug engageable in arecess of the bore 460, to prevent rotation of the male component 464with respect to the body component 412 when installed.

The body component 412 is preferably made of any suitable metal, such astitanium alloy or cobalt chrome. The body component 412 has regionswherein the body component body is porous and regions wherein the bodycomponent body is solid (i.e. non-porous). The porous regions maycomprise a three dimensional porous network structure of pores. Such abody component can be manufactured using an Electron Beam Melting (EBM)machine (e.g. from Arcam AB). In the Electron Beam Melting process, anelectron beam gun is used to selectively melt metal powder in a vacuumchamber to produce regions of solid metal and voids, arranged to createthe desired size, shape, and pattern of holes in the distal and proximalportions of the body component. The body component 412 may have one ormore 3D porous regions, with non-porous regions between. Alternatively,the body component may comprise regions of differing porosity. Forexample, the body component may have one or more regions of highporosity, one or more regions of lower porosity and optionally, one ormore regions which are non-porous. Porosity is the ratio of the volumeof pores to the total volume taken up by the material and pores. Highporosity areas of the body component enhance tissue ingrowth (skinand/or muscle) with the body component. However, high porosity areas areweaker than low porosity/non-porous areas of a body component.Therefore, it is advantageous to have higher porosity regions combinedwith low/non-porous regions in the body component, to provide a bodycomponent which promotes tissue ingrowth, whilst retaining strengthcharacteristics.

Referring to FIG. 5, the peripheral surface of the body component 212surrounding its longitudinal axis comprises a porous region of material412 a, and the inner region 412 b comprises a longitudinal core of solidmetal for strength purposes. The body component 412 is shaped as atrochanter replacement component, shaped to correspond with ananatomical trochanter of the femur. The body component 412 has a greatertrochanter portion 470 at its proximal end, shaped to correspond to ananatomical greater trochanter. The enlarged greater trochanter portion470 of the body component is within the porous region 412 a of the bodycomponent, such that there is a large surface area for attachment ofresidual muscle from the patient, in particular the abductor muscle.Between the distal and proximal ends of the body component 412 is amid-portion of the body component, which has a substantially circularcross-sectional shape. The outer surface of the mid-portion of the bodycomponent 412 is porous to a depth of a few millimetres (preferably adepth of around 4 mm). The outer porous surface of the body component412 provides a greater surface area for attachment of tissue. Preferablythe pores of the porous regions have pore size diameter of around350-700 microns. Most preferably, the average diameter of theapertures/pores is around 700 microns in diameter, as apertures/pores ofthis size have been found to enhance tissue ingrowth, since theapertures/pores are large enough not to restrict dermal invasion. Theporous metal may be treated with a protein coating such as laminin orfibronectin to enhance cell attachment. The porous metal regions may becoated with hydroxyapatite (HA) using a plasma coating method or otherline of site method. Additionally the inner pores may be coated with HAby a solution deposition method which may or may not involve electrodeposition of a calcium phosphate material.

The outer surface region of the body component 412 includes a pluralityof large holes 471, to promote muscle, tendon and/or fascia tissueattachment with the body component. Preferably the holes arethrough-holes, of the order of around 1 to 2 mm in diameter, andpreferably around 2 mm in diameter. These macro-sized apertures/poresare large enough to allow a needle and polymer suture material (such asFiberwire®) to pass through, such that muscle can be secured to the bodycomponent using sutures. The sutures may be permanent or temporary. Thispromotes tissue integration following implantation. After implantation,over time, muscle tissue can ingrow through the macro-sized holes andalso the micro-sized pores of the porous regions, further securing thebody component to the nearby tissue. This then allows the subject tomove the body component using their residual muscle, allowing thesubject to pivot the body component about the subject's hip socket.

The distal end 472 of the body component 412 has a largercross-sectional area than the mid-portion of the body component 412. Thedistal end 472 provides a flange, extending outwardly from thelongitudinal axis of the body component 412. The distal end 472 liesunder the epidermis 414 a and the dermis 414 b layers of the skin. Aswith the flange assemblies of the embodiments of FIGS. 1 to 4, thedistal end 472 provides a large surface area for integration of skin andfibrous tissue with the body component. Referring to FIG. 6A, the distalsurface of the distal end 472 is preferably convexly curved in shape,helping to prevent stresses being applied to the soft tissues that lieover the peripheral edge of the distal end when installed. Preferably,the flange shaped distal end 472 of the body component is porous toenhance attachment of skin tissue to the distal end; this preventsmovement of the body component relative to the skin, helping the skinheal around the device and preventing epithelial downgrowth andinfection. Dermal tissues may be attached to the distal end 472 bysutures which pass through 1-2 mm holes in the distal end 472 (not shownin the figures), similar to the holes 471.

If the intracorporeal body component 412 is installed in a patientwithout installation of the removable portion 461, to serve as a stumpfor supporting an exoprosthesis socket, in order to prevent spinning ofthe exoprosthesis socket the distal end 472 of the body component 412may be non-circular in cross-sectional shape transverse to the directionof insertion to the body; the non-circular distal end resists rotationof the socket relative to the stump. For example, the flange or expandeddistal part may be oval in shape. Alternatively, the flange or enlargeddistal portion may be utilised adjacent to the subject's bone (but notas a stump extender) to provide rotational stability to a socket. Inthis case, the flange could be rigidly fixed to a residual bone (ratherthan coupled articulatingly with an intracorporeal joint component)using an intramedully stem or other suitable bone attachment means.

Typically, the body component will be around 100 mm in length from thedistal end 472 to the proximal end of the greater trochanter portion470. The diameter of the widened distal end 472 may be around 32 mm,with the distal bore portion 460 a being around 12 mm in diameter.

Referring to FIG. 5, the body component 412 includes a femoral neck 473with a trunion 474 to which a femoral head (not shown in FIG. 5) isattached in use.

FIGS. 7 and 8 show two possible types of femoral head and prosthetic cupassembly that can be used with the body component of FIGS. 5, 6A, 6B, orin the embodiments of FIGS. 1 and 2 (similar ball and socket systemscould be used for the prosthetic humeral head and cup component of FIGS.3 and 4). In each of the embodiments of FIGS. 7 and 8, there is afemoral head 475 having a corresponding trunion fitting 474 a that fitsonto the trunion 474 of the percutaneous device. Both the systems ofFIGS. 7 and 8 are constrained ball and socket systems. Non-constrainedsystems rely on the downward force of the body through the joint and/orthe tension created by the soft tissue, including muscles, ligaments andtendons to retain the prosthesis in its implanted position. Constrainedsystems include mechanisms for preventing dislocation of the components.FIG. 7 shows a femoral head 475 inserted in a prosthetic cup 476, and isa constrained cup system. The cup 476 has a greater than hemisphericalcoverage around the femoral head 475, such that the head is constrainedwithin the internal diameter of the cup 476, thus preventing subluxationor dislocation of the head and cup. The femoral head 475 fits into thecup 476 via a snap-fit. The cup 476 is preferably made of polyethylene,more preferably ultra high molecular weight polyethylene. The cup 476 isimplanted at the patient's acetabulum in use.

FIG. 8 shows an alternative constrained system. The system includes ametallic shell 477 that is implanted at the patient's acetabulum. Themetallic shell 477 has a polyethylene bearing insert 478 that sitsinside it, the liner 478 preferably being made of preferably ultra highmolecular weight polyethylene. The femoral head 475 is inserted in thebearing insert 478 and a ring 479 is attached to the face of themetallic shell 477, constraining the head and preventing the head fromdislocating. The ring 479 is preferably threadedly engaged to themetallic shell 477. The system of FIG. 8 may optionally omit the bearinginsert 478, such that the femoral head bears directly against themetallic shell 477.

Referring to FIG. 9, this shows a percutaneous device 510, forming ajoint replacement prosthesis, for installation in a subject that has hada transfemoral amputation. This shows a percutaneous device that can beused with a total joint replacement other than a shoulder or hip joint.The percutaneous device 510 has an intracorporeal portion 512 whichresides under the skin 514 when the device is installed and anextracorporeal portion (not shown) which extends from the skin when thedevice is installed. The percutaneous device of FIG. 9 comprises atibial component of a knee joint, having a tibial articulating component580 at the proximal end of the intracorporeal portion in use, whicharticulates with a separate endoprosthesis 550 comprising a femoral kneehinge component having a condylar surface 583 for articulating with thetibial articulating component 580 of the percutaneous device 512. Theproximal end of the endoprosthesis 550 includes a stem 584 for insertioninto the intramedullary cavity of the patient's femur (not shown), toanchor the endoprosthesis 550 to the bone stump.

Like the FIG. 5, 6A, 6B embodiments, the intracorporeal portion 512 hasa bore 560 for receiving a removeable portion (not shown) that includesa male portion for insertion in the bore 560 and an extracorporealportion that extends from the intracorporeal portion and the skin whenthe removable portion is installed. As with the FIG. 5, 6A, 6Bembodiments, the distal end 572 of the intracorporeal portion 512 has alarger cross-sectional area than the mid-portion of the intracorporealportion. The distal end 572 provides a flange, extending outwardly fromthe longitudinal axis of the intracorporeal portion 512. As with theflange assemblies of the embodiments of FIGS. 1 to 4, the distal end 572provides a large surface area for integration of skin and fibrous tissuewith the intracorporeal portion. The distal surface of the distal end572 is preferably convexly curved in shape, helping to prevent stressesbeing applied to the soft tissues that lie over the peripheral edge ofthe distal end when installed.

Like the body component of FIGS. 5, 6A and 6B, the intracorporealportion 512 has a plurality of through-holes 571 passing through thebody along it's peripheral edge. These allow muscle, tendon andfascia-tissue to attach to the device 512. Preferably the holes arearound 2 mm in diameter, and are large enough to allow a needle to passthrough, for securing tissue to the device 512. By securing tissue suchas muscle, tendon and fascia-tissue attachment to the device 512, thesubject can move the percutaneous device 512 using their residualmuscle, allowing the percutaneous device 512 (the tibial component) tobe pivoted relative to the femoral component 550. Like the bodycomponent of FIGS. 5, 6A and 6B, the intracorporeal portion 512 also hasa core region 512 b of solid metal for strength purposes and a porousregion of material 512 a surrounding the core 512 b.

In use, the bore 560 receives a removable component (not shown) havingan extracorporeal portion that extends from the skin in use. Theextracorporeal portion of the removeable component has means forattaching an exoprosthesis to the extracorporeal portion. The rigidconnection of the removable component (not shown in FIG. 9), having anextracorporeal portion, to the percutaneous device 512 allows thesubject to directly move the extracorporeal portion of the percutaneousdevice using their muscle, and therefore to move an exoprosthesissecured to the extracorporeal portion of the percutaneous device.

It will be understood that the system of FIG. 9 could equally be appliedto provide a total joint replacement for other joints, such as an elbowjoint for a patient having undergone a transhumeral amputation. In suchcases in the past, a patient would use an exoprosthesis having a socketfor receiving the humeral stump and an exoprosthetic elbow joint, tosecure the prosthesis to the stump. The advantage of a percutaneousdevice according to the invention for use in a joint replacement is thatthe joint is contained within the patient's body, and is not part of anexoprosthesis. By integration of the muscle, fascia tissue and tendonswith the percutaneous device, the patient can have direct control overthe replacement joint using their residual muscle, rather than relyingon body control or myoelectric control of an exoprosthetic joint thatwould be required

The percutaneous devices of the various embodiments of the invention arepreferably made of titanium, titanium alloy or cobalt chrome, in orderto provide the percutaneous prosthesis with high strengthcharacteristics. It is important that the percutaneous prosthesis willnot be liable to bend or break when the extracorporeal portion issubjected to large forces, therefore the percutaneous prosthesis mustcomprise a strong, rigid structure. The extracorporeal portion of thepercutaneous device may include a safety device comprising linkage whichbreaks under an unusual load such as, for example, one caused by thepatient falling. This will allow the extracorporeal portion to detachfrom the intracorporeal portion without causing damage to the skin (orbone, if the percutaneous device is bone anchored).

For the embodiment of FIG. 3, in which the percutaneous device 210 isbone anchored, the threaded shank 230 may be substituted with othersuitable attachment means for securing the device to the scapula. In theembodiment of FIG. 4, in which a glenoid prosthesis component 350 isbone anchored, the threaded shank 351 may be substituted with othersuitable attachment means for securing the component to the scapula.

In the various embodiments, the intracorporeal portion of thepercutaneous device may be given a surface treatment to encourage muscleor dermal integration with the device. Such surface treatments includegiving the surface a micro-pitted structure and/or coating the surfacewith adhesion proteins such as laminin or fibronectin which encouragefibrous growth into the surface of the device. A surface is provided onthe intracorporeal portion which is porous and promotes fibrous tissueingrowth. Suitable materials for coating the surface include aluminaoxide ceramics or hydroxyapatite. This surface, preferably after beinggiven a porous surface treatment, is coated with an adhesion promotingprotein, e. g. by spraying the prosthesis with a solution of theadhesion-promoting protein, by dipping the prosthesis in a concentratedsolution of the protein and freeze drying, or by dipping into a sterilesolution of the adhesion-promoting protein prior to installation.

In the embodiments of FIGS. 1-8, the surface of the ball component 20,120, 220, 475 of the percutaneous device will preferably have a surfaceof low-friction material, such as ultra-high molecular weightpolyethylene (UHMWPE), to provide a suitable bearing surface forarticulating with the corresponding socket. In the embodiment of FIGS.4, the surface of the ball component 352 of the glenoid prosthesiscomponent 350 will preferably have a surface of low-friction material,such as ultra-high molecular weight polyethylene (UHMWPE), to provide asuitable bearing surface for articulating with the corresponding socket.In the embodiment of FIG. 4, the articulating surface of the socketcomponent 320 of the percutaneous device will also preferably have asurface of low-friction material, such as ultra-high molecular weightpolyethylene (UHMWPE), to provide a suitable bearing surface forarticulating with the corresponding ball.

Prior to installing the percutaneous device, the hypodermis ispreferably surgically removed. The removal of the hypodermis surgicallyduring the amputation and installation procedure assists in stimulatingattachment of the skin to the device and thereby prevents shear forceson the skin separating the epithelial cells at the interface.

In the various embodiments, the extracorporeal portion of thepercutaneous device that extends from the skin surface may be given anon-stick surface on its exterior portion. Suitable materials includefluorinated polymers such as polytetrafluoroethylene, siliconisedpolymers and diamond-like carbon. Alternatively the outer surface of theextracorporeal portion may be polished to provide a non-stick, lowsurface energy outer surface. The presence of a non-stick surfacediscourages bacteria from attaching to the prosthesis and helps toprevent infection. The non-stick surface may be applied to the exteriorof the extracorporeal portion using the technique of chemical vapourdeposition (CVD). The use of CVD is well known in the art for applying asurface of diamond-like carbon. When applying a surface layer ofdiamond, as disclosed in EP B-0545 542 the method generally involvesproviding a mixture of hydrogen or oxygen gas and a suitable gaseouscarbon compound such as a hydrocarbon, applying energy to that gas todissociate the hydrogen into atomic hydrogen or the oxygen into atomicoxygen and the carbon into active carbon ions, atoms or CH radicals andallowing such active species to deposit on the substrate to formdiamond. The energy to cause dissociation may be provided in a number ofways common to the art, for example by hot filament or by microwavesource. A non-stick surface fluorinated polymer or silicone polymer maybe applied to the extracorporeal portion of the percutaneous device bypolymerising a monomer or prepolymer in contact with the component.

It may be convenient to apply the low energy surface treatment to theextracorporeal portion while masking the remaining components of theprosthesis. Also, the intracorporeal portion of the prosthesis may betreated with the adhesion-promoting protein after applying the lowenergy surface to the extracorporeal portion, and it may be desirable tomask the extracorporeal portion while applying the adhesion-promotingprotein.

The flange assembly 18, 118, 218, 318 and distal end 472, 572 of thepercutaneous devices of the figures may have through-holes, throughwhich dermal and/or muscle tissue can integrate. The flangeassembly/distal end may have surface treatments to encourage muscle ordermal integration with the device. Such surface treatments includegiving the surface a micro-pitted structure and/or coating the surfacewith adhesion proteins such as laminin or fibronectin which encouragefibrous growth into the surface or with alumina oxide ceramics andhydroxyapatite. The flange assembly/distal end may be different shapes.Alternatively, the percutaneous device may have no flange assembly.

Each of the devices described may be provided as a single piece orprovided as a set comprising modular components that are assembledtogether.

The device may be provided as a modular kit, wherein components of thedevice are provided separately and are connected together, some of thecomponents being provided optionally in different sizes and/or withattributes such as different surface coatings, or in different shapes orsizes. For example, the intracorporeal portion of the device may beprovided with a removable ball or socket component in different sizes,for providing a prosthesis for anatomical or reverse anatomicalball-and-socket joint replacement as shown in FIGS. 2 and 4respectively.

Where an artificial limb is connected to the percutaneous device of anyof the above described embodiments, the artificial limb may simply be acosmetic/passive limb to restore the subject's anatomical shape.Alternatively the artificial limb may be controlled using controlsystems known in the prior art. For example, the artificial limb may becontrolled by the subject's own body power, such as usingcable-activation, or the artificial limb may incorporate a power sourceto activate the prosthesis using myoelectric control.

1-40. (canceled)
 41. An intracorporeal portion of a percutaneous device,the intracorporeal portion having an articulating component forarticulating with an articulating surface, wherein the articulatingcomponent is intracorporeal when installed in a subject.
 42. Anintracorporeal portion according to claim 41, wherein the articulatingcomponent is integral with or rigidly coupled to the intracorporealportion of the percutaneous device in use.
 43. An intracorporeal portionaccording to claim 41, wherein the articulating component comprises aball component and the device articulates with an articulating surfaceof a ball and socket joint, when implanted.
 44. An intracorporealportion according to claim 41 wherein the articulating componentarticulates with an articulating surface of a hinge joint whenimplanted.
 45. An intracorporeal portion according to claim 41, whereinthe intracorporeal portion comprises a proximal end and a distal end,the articulating component being located at the proximal end of theintracorporeal portion when installed in a subject.
 46. Anintracorporeal portion according to claim 41, wherein the articulatingcomponent articulates with a natural articulating surface of a subject'sjoint in use.
 47. An intracorporeal portion according to claim 46,wherein the articulating surface is a hip socket or a shoulder socket ofa subject, or is a prosthetic bearing surface installed in a hip socketor shoulder socket of a subject in use.
 48. An intracorporeal portionaccording to claim 45, wherein the articulating surface is a condylarsurface of a subject's knee joint and the articulating component is acorresponding tibial hinge component for articulating with the condylarsurface.
 49. An intracorporeal portion according to claim 46, whereinthe articulating surface is a condylar surface of a subject's knee jointand the articulating component is a corresponding tibial hinge componentfor articulating with the condylar surface.
 50. An intracorporealportion according to claim 41, wherein the articulating componentarticulates with a prosthetic articulating surface in use.
 51. Anintracorporeal portion according to claim 50, wherein articulatingsurface is a prosthetic articulating surface of an endoprosthesis. 52.An intracorporeal portion according to claim 50, wherein thearticulating component comprises a socket component, the socketcomponent articulating with a ball component of a bone anchoredendoprosthesis in use.
 53. An intracorporeal portion according to claim51, wherein the articulating component comprises a socket component, thesocket component articulating with a ball component of a bone anchoredendoprosthesis in use.
 54. An intracorporeal portion according to claim50, wherein the articulating component comprises a tibial component forarticulating with a femoral hinge component of a knee endoprosthesis.55. An intracorporeal portion according to claim 51, wherein thearticulating component comprises a tibial component for articulatingwith a femoral hinge component of a knee endoprosthesis.
 56. A kit for ajoint prosthesis, the kit comprising an intracorporeal portion accordingto claim 50 and an endoprosthesis having an articulating surface forarticulating with the articulating component.
 57. A kit for a shoulderor hip joint disarticulation prosthesis, the kit comprising anintracorporeal portion according to claim 50 and an endoprosthesishaving a ball component and a bone anchoring component for rigidlyattaching the endoprosthesis to bone in use.
 58. A kit according toclaim 57, wherein the endoprosthesis has a body portion for mountinginto bone, the body portion having a substantially frustoconical taperwith an integral screw formation extending terminally therefrom wherebywhen the endoprosthesis is fixed in place to bone by the screwformation, the taper of the body assists in stabilising theendoprosthesis.
 59. An intracorporeal portion according to claim 41,wherein the articulating component is a ball component.
 60. Anintracorporeal portion according to claim 59, wherein the ball componentis substantially spherical.
 61. A kit comprising an intracorporealportion according to claim 41, the kit further comprising anextracorporeal component for location exterior to the skin, theextracorporeal component being integral with or coupled to theintracorporeal portion in use.
 62. A joint prosthesis including anintracorporeal portion device according claim
 41. 63. A method ofinstalling in a subject an intracorporeal portion for a joint prosthesisas claimed in claim 41, the method comprising the steps of (i)implanting the intracorporeal portion under the skin; (ii) coupling thearticulating component with the articulating surface such that thearticulating component can articulate with the articulating surface inuse.